What ever it takes! I don’t think there is anything that anyone can say to magically stop you changing your motion, you need to work on it (I’m not saying its easy).
it doesn’t matter what lick you use - maybe have a couple to give you variety. My 2 cents on it is that you ensure that the pattern is simple for the lefthand and doesn’t move around too much, taking your focus away from your picking hand. @Pepepicks66’s lick is good in that respect in that you can repeat the 1st tiny chunk in isolation and moving down tbe neck as it becomes more 2nd nature and staying on one string at a time. What I did which helped was broadly the below, but do whatever you fancy and try not too ftustrated- it will come. It looks like you have found a picking motion that might work, there are others that haven’t got that far so don’t lose heart:
- get the tremolo going, with you fretting hand ready to play, ensuring that your tremolo is using your efficient motion.
- Once you can smoothly play your tremolo long enough for the duration of the repeatable chunk, after a bar or 2 of the tremolo bring your fretting hand in (preferably without looking) and play a few bars of the pattern. During this your focus is on you picking hand maintaining that efficient motion - Do not worry about your fretting hand or how sloppy it might sound, this is to be expected. You only need to attempt a few bars at a time, this will conserve energy and keep the focus on getting the hands together. However, as it becomes easier/smoother, you will be able to play it repeatedly for much longer.
I’d definitely advise to do this without a metronome, because its a process of trial and error - the metronome will add a certain amount of timing pressure that again distracts you from the goal here.
Take a good handful days to attempt this and let us know how things go. Don’t make this your entire practice session otherwise you will acheive a Gollum level of obsession - not healthy. Make sure you keep it fun and inject this multiple times in between playing and jamming etc.